1. Field of the Invention
This invention relates to a new computing apparatus and method for managing a database. More specifically, it relates to an apparatus and method for synthesizing from a graphic language query an equivalent linear language query for accessing a relational data base.
2. Description of the Prior Art
An example of a linear query language is provided by the IBM Structured Query Language (SQL), as is described in SQL/Data System Terminal User's Guide, IBM Publication SH24-5016-0 and SQL/Data System Application Programming, IBM Publication SH24-5018-0. Such a linear query language provides for defining, accessing, and modifying multiple views of stored tables in a relational data base, such as is described in M. W. Blasgen, et al, "System R: An architectural overview", IBM System Journal, Vol. 20, No. 1, 1981, pp. 41ff.
An example of a graphic query language is provided by the IBM Query-by-Example (QBE), as is described in Query-by-Example Terminal User's Guide, IBM Publication SH20-2078-0. Such a graphic query language also provides for defining, accessing, and modifying stored tables in a data base, and provides a particularly "user friendly" format for the terminal operator, such as is described in M. M. Zloof, "Query-by-Example: a data base language", IBM System Journal, Vol 16, No. 4, 1977, pp. 324ff.
The SQL and QBE query languages have each been designed to access data bases, but heretofore a data base managed by one could not be accessed by the other. Consequently, there exists a need to enable a terminal operator, or user, to access a data base according to a graphic query language even where the data base manager requires that queries be expressed according to a linear query language.